Boyink! - Spring Forward on the Web

or, “How To Make Two $5 Bikes Into One $10 Bike”.

Here’s our latest “garage fun” project - a 20” tandem for kids, made from two inexpensive single-speed kids bikes.  One bike was a girls version that my daughter outgrew.  The other bike is a boys version snagged from the neighbor’s garbage pile on junk day.  The bike was “well-loved” but functioning with tires that were holding air.

To start with I cut off the rear frame portion on the boys bike (intended for the front of the tandem), and removed the handlebars, stem, front wheel and fork from the girl’s bike.

The headset tube from the rear bike fit nicely over the seat post tube of the front bike, so I did that and ran a bead of weld around that spot.  I then connected the two bottom brackets with a chunk of 1” square tubing.

For the rear handlebars I just cut a gap in the bottom portion so that they would slip over the rear bike frame, and I welded them in place.  I was able to keep the front seat height-adjustable by using a length of threaded rod for a seat post.  I welded a washer/nut combination to the top of the rear bike headset tube, and added a second nut to tighten the seat in place.  The seat needs to be removed in order to change the height, but it’s a small inconvienence.

Here is the bike getting a test-fit by the intended victi….uhh….riders.

Here is the bike with pedals and chain added back on.  As you can see the droop in the bottom portion of the chain was an issue:

The solution was to take the spare rear wheel apart, and cut down the axle/sprocket to use as an idler sprocket on the tandem’s lower frame - although the chain still isn’t engaging the top of the sprocket as I’d prefer.  Another sprocket might be in order.

And the inaugural test ride - in 35 degree Michigan winter, with a fresh 2” of slop on the roads and a light rain falling:

And the boy going for a solo test ride.  The two kids tried riding it together but the snow and rain proved too big a distraction for learning the “coordinated launch” required:

Update:  Here’s the latest chain arrangement which seems to be working (until a stray pantleg helps it off the sprocket).  I added a small gear from a junk derailer that the local bike store donated to the project:

And finally, success from the target users of the bike…

So far it’s been a fun and cheap project - all I’ve had to purchase is a fresh bottle of welder gas.  Once the weather gets warmer we’ll sand down the frame and shoot a fresh coat of color on it - maybe it’ll look less like the results of a kids biking accident…

Update: And here’s the finished product after a $10 paint job and $12 in new handlegrips.  The color is Rustoleum Safety Blue:

Comments are closed, but you can read the comments other people left.

1. Olivia on February 26, 2007

   Wow, Mike, that’s impressive. I have a tandem that I used to ride with my husband; I can tell you that you saved A LOT of money plus used A LOT of creativity setting it up this way.

   I admire you all for riding in the snow. That truly takes committment. I won’t feel sorry for myself freezing up here in the Pacific Northwest after this.

   I think the bike looks great!

2. Boyink (Author) on February 26, 2007

   Thanks Olivia…  I was working on the bike in the garage and wondering if I’d get to test it out or not due to the weather, but then “Born To Be Wild” came on the radio, and there was just no refusing the moment…:)

3. Eric on April 25, 2007

   Cool bike, Mike.

   I once helped a friend restore a curvy old Schwinn for his girlfriend. We layered 12 coats of candy red, infused with red glitter. The paint seemed to be as deep as the bike was long. It was quite beautiful.

   The girlfriend left him shortly after that. I should have made her an offer on the bike before they got too separated.

   I certainly did take pause at the Jeep in the background! Sweetheart of a machine.

   Eric

4. Boyink (Author) on April 25, 2007

   Hey Eric - good to hear from you.

   Stay tuned on the CJ6 - it’s getting some body fixes, new paint inside the tub, a complete new dash, new wiring harness and an onboard water system…

5. bikeboy on November 22, 2007

   nice bike although here are a few suggestions
   1. instead of extra sprockets you could have shortened the chain (comercialy abailable chain menders)
   2. you could have cut off the tube where the fork would go in and weld that to the back of the tube where the seat goes in so that way the seat is ajustable without the weird thing you did

   Over all good bike i hope yuo post a new page or update this one

6. Boyink (Author) on November 22, 2007

   Heh…suggestions 10 months (and *many* hours of riding) later….uh..thanks?

   1. I tried a shorter chain - the droop was still too much to overcome - you can see it in the pic.

   I also didn’t need any chain mender to change chain lengths - screwdrivers, a punch, and some pliers worked just fine.

   2. The seat rarely needs adjustment, this approach looks better and worked well for welding in that spot.

7. Jeff on February 16, 2008

   Hi,
   Thats a really cool bike.  You did a good job on the welding.  I once tried to weld small electric motor onto a bike I had, and it turned into a year long project. 
   I think that I was using the wrong type of welder maybe (old stick welder).
   When I finally finished it only lasted a couple days :(

   Jeff

   p.s. be carefull riding in the snow!

8. TY on February 18, 2008

   Yeah, but can you make 4 - $5 dollar bikes into one $20 dollar bike?!?#? lol.
   Tandem bicycles are a lot of fun!

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